Elements Question

[Piper Juunanagou]

Aren't the elemental powers just a manipulation/specialized usage of someone's ki (and thus supernatural), and not actually rooted in the actual elements of the world? Someone with the elemental ice or water power is making their water out of ki and not hydrogen and oxygen (or at least that's how I've always perceived it...staff might have a completely different opinion).

I guess I just don't see how removing oxygen would impede someone's ability to use their ki (aside from asphyxiating them, I guess).